This invention relates to power distribution systems and to methods and apparatus for controlling and protecting such power distribution systems, with emphasis on power distribution systems used in both military and commercial nautical applications and large land transportation vehicles.
Electrical power distribution systems normally include power sources and many loads, with the loads connected to the sources by branches. Typically, those branches connect together at nodes. The nodes and branches may be provided in a hub and spoke configuration.
Typically, nodes are custom-tailored to fit a particular need of the electrical power distribution system at a particular node location. Small nodes may handle small blocks of power. Large nodes may handle large blocks of power and include numerous functions performed at the node. One type of node is a power panel, which is typically a small node and in the prior art, incorporates some degree of standardization.
Power systems may generally be characterized as low voltage or high voltage power systems. Low voltage power systems for purposes herein are considered to be power systems in which voltage is less than about 1,000 volts.
In low voltage power systems, the nodes vary in power handling capacity from less than 10 kilowatts to over 5 megawatts. Node functions vary from simple distribution to very complex distribution, automatic switching, frequency conversion, voltage conversion, power quality regulation and various types of system protection control and multiple operating control functions.
Current practice in designing electrical power distribution systems, either for original construction or for modification and upgrading, is to identify the functional and characteristic requirements for each node. Node functional requirements establish the number of incoming and outgoing circuits to and from the node.
In current commercial practice, when a power system is designed, the power system designer also identifies the type(s) of switching devices to be utilized at a node and the rating of each such device. The designer further identifies the type of control available for each node and whether such control should be manned or automatic. Current practice is also for a power system designer to specify the type of protection, if any, to be provided at a given node.
In current commercial practice, it may be necessary or desirable to perform frequency and/or voltage conversion at nodes.
Typically, all of the equipment required to be present at a given node is not produced by a single entity, making it necessary to secure various components used at a node from different manufacturers. Conventionally, a switchgear producer may acquire and assemble many of the components and much of the equipment for each node, but must design and custom engineer each node before each node can be produced; this is especially true with more complex nodes. As a result, each node typically takes on its own identity and is not thereafter easily changed. This means the power distribution system which eventually results loses flexibility early in the design process for the system, since lead time for purchase of a node and node equipment includes the time required to design or custom engineer certain equipment required to facilitate the functions to be performed at the node.
Conventionally, a power system node may contain several distinct elements which are not preassembled. In such case, it is necessary to install individual components, connect those components after installation and then test the installed, connected components for proper operation, after those components have been installed at a given node.
The primary thrust of this invention is towards low voltage electrical power systems, namely systems in which the voltage is less than about 1,000 volts.
This invention provides an electrical power distribution system which includes a plurality of branches for carrying power with the branches being interconnected at nodes. The system further includes at least one means for supplying power for distribution within the system where the power supply means is connected to a branch. The system further includes at least one load, consuming power supplied to the load, where the load is connected to a branch other than the branch having the power supply means connected thereto.
In another of its aspects, this invention provides scaleable, standardized integrated power node control centers which are modular in construction to facilitate accommodation of changes in power system requirements and which may be easily upgraded in the event of future changes to the power distribution system.
In yet another of its aspects, this invention provides a bus structure which accommodates a variety of different types and sizes of modules which can be connected together to define a desired integrated power node control center. This standardized bus structure accommodates a variety of components for switching, conversion and/or power regulation.
In another of its aspects, this invention provides multiple levels of integrated power node control centers where the levels are based on the amount of power a node handles and on the number of incoming and outgoing branches or circuits.
In a further aspect this invention provides an electrical power node control center which includes a plurality of bus bars for carrying electrical power, means for inputting power to the node control center for distribution within the node control center by the plurality of bus bars, at least one power distribution device for regulating and controlling power distributed by a node associated with and preferably contained within the node control center, means housing a plurality of functional distribution devices for controlling power flow between said first input and one or more outputs from said node contained within said control center, means for connecting said distribution devices to the plurality of bus bars, a control system for monitoring input power to the node and output power of each output connection from the node, a control system for monitoring the electrical system data of the node and commanding at least one of said functional distribution devices that disconnect the node output circuit or to stop power flow to the connected output circuit if an undesirable condition is detected on the output circuit, wherein said control system utilizes programmable means for performing such monitoring and commanding, a control system connected to the overall electrical central control which by input signal changes the state of one or more of the functional distribution devices from a given state to an opposite state, a control system for also monitoring the health of the functional distribution devices and sending a command to automatically alter the device for self-correcting, turning the device off or sending a warning signal to the central control system and where the control systems include monitoring or sensing means, processing means which process the sensed data according to a predetermined or adaptive algorithm and having an output function which may command action, display information or record data.
The integrated power node control center preferably performs functions selected from the group including switching, voltage conversion, frequency conversion and voltage regulation.
In yet another of its aspects this invention provides an integrated power node control center having at least one operating control module and at least one protection control module adapted for connection to a bus bar structure for performing one or more of the control functions where the control modules perform one or more functions selected from the group of protection control functions which include but are not limited to over-current protection, ground current protection, over and under voltage protection, over and under frequency protection, differential current protection, phase current imbalance protection and open circuit protection, and wherein the control module performs one or more of the functions selected from a group of operating control functions which include but are not limited to state monitoring of all inputs and of all outputs, health monitoring of all functional power distribution devices, diagnostic monitoring of the control functions, communicating control information to a central control station or other integrated power node control centers, receiving and operating on information and commands from the central control station or other integrated power node control centers, displaying information of the integrated power node control center and such other control functions as may be desirable for proper operation of the integrated power node control center.